(Recent Study Claims) Pioneer Anomaly Solved By 1970s Computer Graphics Technique

[Wilms]

Pioneer Anomaly Solved By 1970s Computer Graphics Technique

A new computer model of the way heat is emitted by various parts of the Pioneer spacecraft, and reflected off others, finally solves one of the biggest mysteries in astrophysics

kfc 03/31/2011

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Spacecraft engineers' first thought was that heat emitted by the spacecraft could cause exactly this kind of deceleration. But when they examined the way heat was produced on the craft, by on board plutonium, and how this must have been emitted, they were unable to make the numbers add up. At most, thermal effects could account for only 67 per cent of the deceleration, they said.

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Previous calculations have only estimated the effect of reflections. So Francisco and co used a computer modeling technique called Phong shading to work out exactly how the the emitted heat is reflected and in which direction it ends up travelling.

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In particular, Phong shading has allowed the Portuguese team to include for the first time the effect of heat emitted from a part of the spacecraft called the main equipment compartment. It turns out that heat from the back wall of this compartment is reflected from the back of the spacecraft's antenna (see diagram above).

Since the antenna points Sunward, towards Earth, reflections off its back would tend to decelerate the spacecraft. "The radiation from this wall will, in a first iteration, reflect off the antenna and add a contribution to the force in the direction of the sun," say Francisco and co.

Lo and behold, this extra component of force makes all the difference. As Francisco and co put it: "With the results presented here it becomes increasingly apparent that, unless new data arises, the puzzle of the anomalous acceleration of the Pioneer probes can finally be put to rest." In other words, the anomaly disappears.


http://www.technologyreview.com/blog/arxiv/26589/


Pioneer anomaly

The Pioneer anomaly or Pioneer effect is the observed deviation from predicted accelerations of the Pioneer 10 and Pioneer 11 spacecraft after they passed about 20 au on their trajectories out of the solar system.

Both Pioneer spacecraft are escaping the solar system, but are slowing under the influence of the Sun's gravity. Upon very close examination of navigational data, the spacecraft were found to be slowing slightly more than expected. The effect is an extremely small but unexplained acceleration towards the Sun, of (8.74 ± 1.33) × 10−10 m/s2. The two spacecraft were launched in 1972 and 1973 and the anomalous acceleration was first noticed as early as 1980, but not seriously investigated until 1994.<1> The last communication with either spacecraft was in 2003, but analysis of recorded data continues.

http://en.wikipedia.org/wiki/Pioneer_anomaly

[Ian David]

1. ...

[Ian David]

2. I wonder if we could train a laser on the antenna and accelerate it like a solar sail. n/t

[caraher]

3. Yes, but...

you won't get much acceleration. You also have serious problems with beam spreading thanks to diffraction at this kind of distance.

[FiveGoodMen]

4. And if the beam didn't spread, seems like you'd need some rather spectacular aim to hit it.

[Wilms]

5. .